[R] Ordered logistic regression in R vs in SAS

[Frank E Harrell Jr]

Emilie Berthiaume wrote:
> I tried the following ordered logistic regression in R:
> 
> mod1 <- polr(altitude~sp + wind_dir + wind_speed + hr, data=altioot)

You might also try
library(Design) # also requires Hmisc package
mod1 <- lrm(....)
mod1
summary(mod1)
anova(mod1)

Frank Harrell

> 
> But when I asked The summary of my regression I got the folloing error message:
> 
> 
>>summary (mod1)
> 
> 
> Re-fitting to get Hessian
> 
> Error in optim(start, fmin, gmin, method = "BFGS", hessian = Hess, ...) : 
>         the initial value of 'vmin' is not finished.
> 
> I decided to try it in SAS with the following program:
> 
> PROC LOGISTIC
> DATA=altioot;
> CLASS sp wind_dir ;
> title "mod1";
> output out=mod1;
> MODEL altitude = sp wind_dir wind_speed hr;
> RUN;
> 
> And it ran well with an good output.  So my question is: Can someone tell me what is the difference between the ordered logistic regression of R and that of SAS?  Does anyone have a suggestion to help me run my program in R?
> 
> Thank you very much,
> 
> Emilie Berthiaume
> graduate student
> Biology Department
> Sherbrooke University
> Sherbrooke, Quebec
> CANADA
> 
> emilie.berthiaume at USherbrooke.ca
> 	[[alternative HTML version deleted]]
> 
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-- 
Frank E Harrell Jr   Professor and Chair           School of Medicine
                      Department of Biostatistics   Vanderbilt University